Western blot analysis revealed that gross p53 and ARF overexpression was more frequent in IL6-/-;Eμ-myc lymphomas [~80% of cases] as compared with IL6+/+;Eμ-myc lymphomas [~40% of cases] suggesting that tumorigenesis in IL-6-deficient mice may specifically select for a loss of p53 function. The gene discussed is IL6; the disease is lymphoma.